The present invention relates to fluid couplings, and specifically fluid couplings for driving a cooling fan device associated with a vehicle.
Fluid couplings for driving a cooling fan device associated with a vehicle are well known. Such known fluid couplings include an output member on which the fan blades are secured and which output member defines a chamber in which the input member of the fluid coupling is mounted. The input and output members of the fluid coupling conventionally include lands and grooves which define a shear space therebetween and a fluid shear medium located in the shear space transmits torque from the input coupling member to the output coupling member. The advantages of such fluid couplings in driving fan cooling devices in vehicles are well known.
The torque transmitted from the input member to the output member is controlled by the amount of viscous fluid in the shear space accordingly; such fluid coupling devices have been constructed in order to provide for removal of fluid from the shear space as well as provision for directing fluid into the shear space in order to control torque transmission. Commonly, such devices include a fluid reservoir chamber and pumping elements which pump fluid from the shear space into the reservoir chamber, and a temperature-responsive valve for controlling the flow of fluid from the reservoir chamber back into the shear space. Such structure operates in order to remove fluid from the shear space when cooling action is not necessary by the fan and provides for directing fluid into the shear space when cooling action by the fan is desired.